1. Field of the Invention
The present invention relates to improvements in a V-type cylinder block of internal combustion engine.
2. Description of the Prior Art
Among various kinds of V-type cylinder blocks of internal combustion engine having two cylinder rows angularly arranged with respect to a crank shaft, a cylinder block 1 as shown in FIG. 4 has been widely used. This cylinder block 1 comprises two cylinder banks angularly disposed with respect to a crank shaft 2, each having cylinders 3 to 5 in a cylinder row 6 and cylinders 7 to 9 in a cylinder row 10. Cylinder heads (not shown) are respectively connected to an upper portion of the cylinders by head bolts (refer to Japanese Preliminary Utility Model Publication No. 60-170048).
In this prior art, a plurality of ribs 11 are formed between the cylinder rows 6 and 10 to increase the strength of the cylinder block 1. However, since each of the ribs 11 is arranged parallel between wall portions of the cylinder rows 6 and 10, it does not have much restraint to torsional vibration generated by combustion in each of the cylinders 3 to 5 and 7 to 9 resulting in deformation of the cylinder block 1.
Recently, a knocking sensor provided on a cylinder block is used for detecting an engine knocking. With such V-type cylinder block 1, the knocking sensor must be disposed every cylinder, causing cost increase.
There is another cylinder block having, between the cylinder rows, a plate portion which is connected with each rib and provides the knocking sensors. With this cylinder block, also, it is impossible to reduce torsional deformation of the cylinder block. Additionally, the engine knocking is detected through the plate portion so that it is difficult to precisely detect the knocking of each of the cylinders (refer to Japanese Preliminary Utility Model Publication No. 59-106029).
It is, therefore, an object of the present invention to provide a V-type cylinder block of internal combustion engine which is free of the aforementioned problems.